The Nexus of Science and Story: Data vs Perceptions of Climate Change

Although the IPCC can be credited with significant efforts to bridge communication between scientist and policy makers, there is still a noticeable discrepancy between the scientific consensus and public perception of the existence and causes of climate change that hamper the implementation of policies aimed at the mitigation and adaptation. Most people gain their understanding of science through the media, and in this contribution I investigate how journalists portray climate change affecting people in a comprehensive case study across Canada.
The study is based on a content analysis of more than 3000 English language newspaper articles published across Canada from 2000 to 2013. I examined how climate or weather related events were portrayed, and whether or not the article linked the event in question to climate change. The reported events were then compared against historical climate data from 1950 to 2013 to determine if the event was correctly or incorrectly attributed to a climate change trend (true or false positives), or was correctly or incorrectly not attributed (true or false negatives).
Perhaps conforming to expectations, temperature and precipitation related events reported in the news media were largely portrayed as harmful to both humans and ecosystems, but articles that attributed events to climate change were in the minority. Only a small number of climate events, such as permafrost thaw in northern Canada and the pine beetle epidemic in British Columbia were consistently linked to climate change. In general, journalists started to reliably attribute events to climate change when the observed climate change signal exceeded 1.5°C. Thus, attribution to climate change only emerges near a threshold that the scientific community considers dangerous (≥2°C). Events linked to changes in precipitation were reliably associated with seasonal anomalies exceeding a 50% increase or decrease over normal conditions but were rarely attributed to long term trends, which was generally correct.
In summary, reporting of climate related events in print media was surprisingly accurate with respect to true positives when the climate change signal exceeded 1.5°C, and also for true negatives when an observed climate change signal was absent. However, for an intermediate warming signal between approximately 0.5 and 1.5°C, I observed a large proportion of false negatives. This represents a missed opportunity for journalists to communicate impacts of global climate change. To better link weather related news stories to moderate climate warming, web-based tools to access historical climate data are provided for journalists to communicate climate change impacts with more confidence at an earlier stage.